Re: [Qemu-devel] [PATCH v4 REPOST 1/2] Add device listener interface

[Paolo Bonzini <pbonzini@redhat.com>]

On 03/12/2014 14:40, Michael S. Tsirkin wrote:
> On Wed, Dec 03, 2014 at 12:29:43PM +0000, Stefano Stabellini wrote:
>> The second patch is already Acked.
>> You just need a review on this one to move forward, right?
>>
>> Andreas, Michael?
> 
> Looks like a generic qdev thing, nothing to do with me.
> 
>> On Wed, 3 Dec 2014, Paul Durrant wrote:
>>> The Xen ioreq-server API, introduced in Xen 4.5, requires that PCI device
>>> models explicitly register with Xen for config space accesses. This patch
>>> adds a listener interface into qdev-core which can be used by the Xen
>>> interface code to monitor for arrival and departure of PCI devices.
>>>
>>> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
>>> Cc: Michael S. Tsirkin <mst@redhat.com>
>>> Cc: Andreas Faerber" <afaerber@suse.de>
>>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>>> Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
>>> Cc: Igor Mammedov <imammedo@redhat.com>
>>> Cc: Markus Armbruster <armbru@redhat.com>
>>> Cc: Thomas Huth <thuth@linux.vnet.ibm.com>
>>> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
>>> ---
>>>  hw/core/qdev.c          |   54 +++++++++++++++++++++++++++++++++++++++++++++++
>>>  include/hw/qdev-core.h  |   10 +++++++++
>>>  include/qemu/typedefs.h |    1 +
>>>  3 files changed, 65 insertions(+)
>>>
>>> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
>>> index fcb1638..4a9c1f6 100644
>>> --- a/hw/core/qdev.c
>>> +++ b/hw/core/qdev.c
>>> @@ -175,6 +175,56 @@ int qdev_init(DeviceState *dev)
>>>      return 0;
>>>  }
>>>  
>>> +static QTAILQ_HEAD(qdev_listeners, DeviceListener) qdev_listeners
>>> +    = QTAILQ_HEAD_INITIALIZER(qdev_listeners);
>>> +
>>> +enum ListenerDirection { Forward, Reverse };
>>> +
>>> +#define QDEV_LISTENER_CALL(_callback, _direction, _args...)     \
>>> +    do {                                                        \
>>> +        DeviceListener *_listener;                              \
>>> +                                                                \
>>> +        switch (_direction) {                                   \
>>> +        case Forward:                                           \
>>> +            QTAILQ_FOREACH(_listener, &qdev_listeners, link) {  \
>>> +                if (_listener->_callback) {                     \
>>> +                    _listener->_callback(_listener, ##_args);   \
>>> +                }                                               \
>>> +            }                                                   \
>>> +            break;                                              \
>>> +        case Reverse:                                           \
>>> +            QTAILQ_FOREACH_REVERSE(_listener, &qdev_listeners,  \
>>> +                                   qdev_listeners, link) {      \
>>> +                if (_listener->_callback) {                     \
>>> +                    _listener->_callback(_listener, ##_args);   \
>>> +                }                                               \
>>> +            }                                                   \
>>> +            break;                                              \
>>> +        default:                                                \
>>> +            abort();                                            \
>>> +        }                                                       \
>>> +    } while (0)
>>> +
>>> +static int qdev_listener_add(DeviceState *dev, void *opaque)
>>> +{
>>> +    QDEV_LISTENER_CALL(realize, Forward, dev);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +void qdev_listener_register(DeviceListener *listener)
>>> +{
>>> +    QTAILQ_INSERT_TAIL(&qdev_listeners, listener, link);
>>> +
>>> +    qbus_walk_children(sysbus_get_default(), NULL, NULL, qdev_listener_add,
>>> +                       NULL, NULL);
>>> +}
>>> +
>>> +void qdev_listener_unregister(DeviceListener *listener)
>>> +{
>>> +    QTAILQ_REMOVE(&qdev_listeners, listener, link);
>>> +}
>>> +
>>>  static void device_realize(DeviceState *dev, Error **errp)
>>>  {
>>>      DeviceClass *dc = DEVICE_GET_CLASS(dev);
>>> @@ -186,12 +236,16 @@ static void device_realize(DeviceState *dev, Error **errp)
>>>              return;
>>>          }
>>>      }
>>> +
>>> +    QDEV_LISTENER_CALL(realize, Forward, dev);
>>>  }
>>>  
>>>  static void device_unrealize(DeviceState *dev, Error **errp)
>>>  {
>>>      DeviceClass *dc = DEVICE_GET_CLASS(dev);
>>>  
>>> +    QDEV_LISTENER_CALL(unrealize, Reverse, dev);

These need to be in device_set_realized.  device_realize and
device_unrealize are just for backwards-compatibility to devices that
still use init/exit.

Also, this has to be call to be _after_ unrealization, i.e. after
setting dev->pending_deleted_event in device_set_realize.

Paolo

>>>      if (dc->exit) {
>>>          int rc = dc->exit(dev);
>>>          if (rc < 0) {
>>> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
>>> index 178fee2..f2dc267 100644
>>> --- a/include/hw/qdev-core.h
>>> +++ b/include/hw/qdev-core.h
>>> @@ -167,6 +167,12 @@ struct DeviceState {
>>>      int alias_required_for_version;
>>>  };
>>>  
>>> +struct DeviceListener {
>>> +    void (*realize)(DeviceListener *listener, DeviceState *dev);
>>> +    void (*unrealize)(DeviceListener *listener, DeviceState *dev);
>>> +    QTAILQ_ENTRY(DeviceListener) link;
>>> +};
>>> +
>>>  #define TYPE_BUS "bus"
>>>  #define BUS(obj) OBJECT_CHECK(BusState, (obj), TYPE_BUS)
>>>  #define BUS_CLASS(klass) OBJECT_CLASS_CHECK(BusClass, (klass), TYPE_BUS)
>>> @@ -368,4 +374,8 @@ static inline void qbus_set_hotplug_handler(BusState *bus, DeviceState *handler,
>>>                               QDEV_HOTPLUG_HANDLER_PROPERTY, errp);
>>>      bus->allow_hotplug = 1;
>>>  }
>>> +
>>> +void qdev_listener_register(DeviceListener *listener);
>>> +void qdev_listener_unregister(DeviceListener *listener);
>>> +
>>>  #endif
>>> diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
>>> index 04df51b..e32bca2 100644
>>> --- a/include/qemu/typedefs.h
>>> +++ b/include/qemu/typedefs.h
>>> @@ -20,6 +20,7 @@ typedef struct Property Property;
>>>  typedef struct PropertyInfo PropertyInfo;
>>>  typedef struct CompatProperty CompatProperty;
>>>  typedef struct DeviceState DeviceState;
>>> +typedef struct DeviceListener DeviceListener;
>>>  typedef struct BusState BusState;
>>>  typedef struct BusClass BusClass;
>>>  
>>> -- 
>>> 1.7.10.4
>>>
>>>